Add README content

README.md

+# Raspberry Pi Setup
+
+### This ansible Playbook does the following things:
+- Install pip3
+- Install jupyter-lab
+- Setup a systemd service for jupyter-lab, enable it (autostart) and start it
+- Jupyter-lab is served on `0.0.0.0:8888` with an empty password. This of course has security implications and should be discussed
+- Install the following python3 packages:
+    - numpy
+    - sklearn
+    - matplotlib
+    - pandas
+    - Pillow
+- On the desktop version of Raspberry Pi OS, `pil` and `numpy` are preinstalled from the APT repository and will be removed in favour the `pip3` versions. This behavior should be discussed, as there might be further problems caused by incompatible packages depending on the use of either APT or pip python packages
+
+### The project is structured as follows:
+- [local.yml](./local.yml): The main playbook file, can be seen as the entry point
+  - [roles](./roles): Contains multiple roles (can be seen as small task specific playbooks). The 
+    roles are called in the [local.yml](./local.yml)
+    - [jupyter-lab](./roles/jupyter-lab/tasks/main.yml): Install jupyter-lab and configure it with a systemd service and autostart
+    - [misc-applications](./roles/misc-applications/tasks/main.yml): Install additional extra applications
+    - [ml-python-packages](./roles/ml-python-packages/tasks/main.yml): Install the machine learning python packages
+
+
+
+# Using the ansible playbook on Raspberry Pi OS
+
+Steps to run the ansible script on a fresh (or not fresh) installation of raspberry pi os:
+```sh
+# Update the APT repo sources
+sudo apt update
+# Install ansible and git. git is already present on the desktop os version
+sudo apt install -y --no-install-recommends ansible git
+
+# Pull and run the ansible scripts from git
+# NOTE: Since the repository is currently private, the gitlab login prompt will shown. When  using 
+# 2FA for gitlab the password login is not possible and an access token is needed. This will be 
+# fixed in the future
+sudo ansible-pull -U https://code.fbi.h-da.de/pse-ai-at-the-edge/raspberry-pi-setup.git
+```
+
+# Notes
+
+## 64-Bit Raspberry Pi OS (Desktop)
+
+There were major problems when trying to install the software on 64-Bit Pi OS. Multiple python packages started to compile C/C++ library code on the device which caused extreme increases of installation times and full failures due to the 1GB RAM on model 3B beeing completely used up. Jupyter-lab also needed an additional dependency (`libffi-dev`) to compile its backend. This behavior occurred when installing packages using `pip3`, but not when using APT. Since some packages are not available, or too old on APT pip can't be fully avoided.
+
+This might be caused by those python libraries depending on C/C++ code which is either shipped precompile or build on device. In this case there might be a precompiled version available for armv7 (32-bit) but not for aarch64 (64-bit), causing the C/C++ code to be compiled on device with the 64-bit OS and not with the 32-bit OS.